FILM

User subroutine to define nonuniform film coefficient and associated sink temperatures for heat transfer analysis.

User subroutine FILM:

can be used to define a node-based, element-based, or surface-based nonuniform film coefficient;
can be used to define sink temperatures as functions of position, time, temperature, node number, element number, integration point number, etc.;
will be called during procedures that allow heat transfer analysis at each node or surface integration point of those surfaces and elements for which node-based, element-based, or surface-based nonuniform film conditions are defined;
ignores any amplitude references for the sink temperature or film coefficient that may appear with the associated nonuniform film definition; and
uses the nodes for first-order heat transfer elements as surface integration points for both element-based and surface-based films.

The following topics are discussed:

User subroutine interface
Variables to be defined
Variables passed in for information

User subroutine interface

      SUBROUTINE FILM(H,SINK,TEMP,KSTEP,KINC,TIME,NOEL,NPT,
     1 COORDS,JLTYP,FIELD,NFIELD,SNAME,NODE,AREA)
C
      INCLUDE 'ABA_PARAM.INC'
C
      DIMENSION H(2),TIME(2),COORDS(3), FIELD(NFIELD)
      CHARACTER*80 SNAME

      user coding to define H(1), H(2), and SINK

      RETURN
      END

Variables to be defined

H(1): Film coefficient at this point. Units are JT⁻¹L⁻² $θ$ ⁻¹. H(1) will be passed into the routine as the magnitude of the film coefficient specified as part of the node-based, element-based, or surface-based film condition definition. If the magnitude is not defined, H(1) will be initialized to zero.
H(2): $d h / d θ$ , rate of change of the film coefficient with respect to the surface temperature at this point. Units are JT⁻¹L⁻² $θ$ ⁻². The rate of convergence during the solution of the nonlinear equations in an increment is improved by defining this value, especially when the film coefficient is a strong function of surface temperature.
SINK: Sink temperature. SINK will be passed into the routine as the sink temperature specified as part of the node-based, element-based, or surface-based film condition definition. If the sink temperature is not defined, SINK will be initialized to zero.

Variables passed in for information

TEMP

Estimated surface temperature at this time at this point.

KSTEP

Step number.

KINC

Increment number.

TIME(1)

Current value of step time.

TIME(2)

Current value of total time.

NOEL

Element number. This variable is passed in as zero for node-based films.

NPT

Surface integration point number. This variable is passed in as zero for node-based films.

COORDS

An array containing the coordinates of this point. These are the current coordinates if geometric nonlinearity is accounted for during the step (see Defining an analysis); otherwise, the array contains the original coordinates of the point.

JLTYP

Identifies the element face for which this call to FILM is being made for an element-based film coefficient specification. This information is useful when several different nonuniform film conditions are being imposed on an element at the same time. See About the element library for element face identification. The key is as follows:

JLTYP	Film type
0	Node-based or surface-based loading
11	F1NU (FNEGNU for heat transfer shells)
12	F2NU (FPOSNU for heat transfer shells)
13	F3NU
14	F4NU
15	F5NU
16	F6NU
-1	Free surface interior to the element at the current time, applicable to the FFSNU FILM type only

FIELD

Interpolated values of field variables at this point.

NFIELD

Number of field variables.

SNAME

Surface name for which this call to FILM is being made for a surface-based film coefficient specification (JLTYP=0). This variable is passed in as blank for both node-based and element-based films.

NODE

Node number. This variable is passed in as zero for both element-based and surface-based films.

AREA

Nodal area for node-based films. AREA will be passed into the routine as the nodal area specified as part of the node-based film coefficient specification. This nodal area is not available for output purposes. This variable is passed in as zero for both element-based and surface-based films.